Magneto-plasmonic heterodimers: Evaluation of different synthesis approaches

Nanomedicine has gained huge attention in recent years with new approaches in medical diagnosis and therapy. Particular consideration has been devoted to the nanoparticles (NPs) in theranostic field with specific interest for magnetic and gold NPs (MNPs and GNPs) due to their peculiar properties under exposition to electromagnetic fields. In this paper, we aim to develop magneto-plasmonic heterodimer by combining MNPs and GNPs through a facile and reproducible synthesis and to investigate the influence of different synthesis parameters on their response to magnetic and optical stimuli. In particular, various syntheses were performed by changing the functionalization step and using or not a reducing agent to obtain stable NP suspensions with tailored properties. The obtained heterodimers were characterized through physical, chemical, optical, and magnetic analysis, in order to evaluate their size, shape, plasmonic properties, and superparamagnetic behavior. The results revealed that the shape and dimensions of the nanocomposites can be tuned by MNPs surface functionalization, as well as by the use of a reducing agent, giving rise to nanoplatform suitable for biomedical application, exploiting the gold absorbing peak in the specific gold absorbing range of GNPs, while maintaining the superparamagnetic behavior typical of the MNPs. The obtained nanocomposites can be proposed as potential candidates for cancer theranostics.     

Simple strategy to tune the charge transport properties of conjugated polymer/carbon nanotube composites using an electric field assisted deposition technique

Work concerning the incorporation of carbon nanotubes (CNTs) in organic semiconducting polymers have now been reported by many research groups, and the electrical properties of polymer/CNT nanocomposites have been extensively studied. In this work, we present a simple procedure to tune the charge transport properties of planar organic polymer films based on poly(3‐hexylthiophene) (P3HT). The polymer/CNT composites are simultaneously processed and oriented from solution using an electric field assisted orientation technique. We first study the behavior of CNTs alone during the alignment procedure and emphasize the main experimental parameters that drive their final orientation on the substrate. By quantitatively analyzing the CNT angular distribution on the substrate, we show that the dielectric constant of the solvent used to disperse and deposit the CNTs is crucial to ensure an efficient orientation, and that a dielectrophoresis‐like orientation procedure occurs. The transposition of this approach to planar P3HT/CNT composites is made by investigating the electric properties in ambient conditions of aligned and non‐aligned devices. Current–voltage characteristics show a drastic increase of the composite conductivity upon addition and alignment of CNTs. Field‐effect transistor charge mobilities are improved by an order of magnitude upon addition of CNT (1 wt%) in P3HT, and another decade is gained using the optimized alignment parameters, without any additional annealing. These results demonstrate the strong potentialities of our approach in the field of printed electronics and organic optoelectronics. © 2013 Society of Chemical Industry     

A review on MnZn ferrites: Synthesis,characterization and applications

Researchers are taking great interest in the synthesis and characterization of MnZn ferrites due to their wide range of applications in many areas. MnZn ferrites are a class of soft magnetic materials that have very good electrical, magnetic and optical properties. The properties of MnZn ferrites include high value of resistivity, permeability, permittivity, saturation magnetization, low power losses and coercivity. The above mentioned advantageous features of MnZn ferrites make them suitable for the use in various applications. In biomedical field these ferrites are used for cancer treatment and MRI. MnZn ferrites are also used in electronic applications for making transformers, transducers and inductors. These ferrites are also used in magnetic fluids, sensors and biosensors. MnZn ferrite is highly useful material for several electrical and electronic applications. It finds applications in almost every household appliances like mobile charger, LED bulb, TV, refrigerator, juicer mixer, washing machine, iron, microwave oven, mobile, laptop, desktop, printer and so on. Therefore, the present review focuses on different techniques for synthesis of MnZn ferrites in literature, their characterization tools, effect of doping on the properties of MnZn ferrite and finally we will discuss about their applications.     

Effect of biogenic and synthetic starting materials on the structure of hydroxyapatite bioceramics

In this study, a synthesis of hydroxyapatite by wet-chemical precipitation route was conducted, using a number of calcium oxide sources. Two biogenic calcium carbonates, which are common in nature, i.e. bird eggshells (Gallus gallus domesticus) and land snail shells (from Arianta arbustorum), as well as commercially available synthetic calcium oxides were used as calcium oxide sources. Calcium oxide starting materials and synthesised calcium phosphate products were investigated. Hydroxyapatite bioceramics obtained from the calcium oxides of different origins had significant differences in microstructure after thermal treatment. Microelement analysis of hydroxyapatite products by inductively coupled plasma mass spectroscopy (ICP-MS) showed that they incorporate different amounts of microelements. The microstructure parameters of the obtained bioceramics were influenced by the presence of multiple trace elements in the structure of hydroxyapatite, which also significantly influenced the crystal lattice parameters. The origin of the calcium oxide starting material has a significant impact on the physicochemical properties and quality of bioceramic implants and, therefore, could also affect the biological properties of these materials.     

Bioceramic composites for orthopaedic applications: A comprehensive review of mechanical,biological, and microstructural properties

Bioceramics have been widely utilized for orthopaedic applications in which the biocompatibility and mechanical properties of the materials are vital characteristics to be considered for their clinical use. Till date, extensive studies have been devoted to developing a range of scientific ways for tailoring the microstructure of bioceramics in order to attain the trade-off of mechanical properties and biocompatibility of the final product. Owing to low reactivity, earlier stabilization and longer functional life of bioceramic, the developed implants are capable of replicating the mechanical behaviour of original bone. As the safety of the patient and its ultimate functionality are the ultimate goal of the selected implant material hence, the present literature survey investigates and brings forth the important aspects associated to the mechanical, biological and microstructural characteristics of bioceramics employed in orthopaedic applications. The review paper majorly focuses on effective utilization of various materials as an additive in bioceramics and processing techniques used for enhancement of properties, enabling the use of material in orthopaedic applications. The influence of various additives on the microstructure, mechanical properties and biological performance of developed bioceramics orthopaedic implants has been elaborately discussed. Furthermore, future prospects are proposed to promote further innovations in bioceramics research.     

Lipid Cubic Mesophases Combined with Superparamagnetic Iron Oxide Nanoparticles: A Hybrid Multifunctional Platform with Tunable Magnetic Properties for Nanomedical Applications

Hybrid materials composed of superparamagnetic iron oxide nanoparticles (SPIONs) and lipid self-assemblies possess considerable applicative potential in the biomedical field, specifically, for drug/nutrient delivery. Recently, we showed that SPIONs-doped lipid cubic liquid crystals undergo a cubic-to-hexagonal phase transition under the action of temperature or of an alternating magnetic field (AMF). This transition triggers the release of drugs embedded in the lipid scaffold or in the water channels. In this contribution, we address this phenomenon in depth, to fully elucidate the structural details and optimize the design of hybrid multifunctional carriers for drug delivery. Combining small-angle X-ray scattering (SAXS) with a magnetic characterization, we find that, in bulk lipid cubic phases, the cubic-to-hexagonal transition determines the magnetic response of SPIONs. We then extend the investigation from bulk liquid-crystalline phases to colloidal dispersions, i.e., to lipid/SPIONs nanoparticles with cubic internal structure (“magnetocubosomes”). Through Synchrotron SAXS, we monitor the structural response of magnetocubosomes while exposed to an AMF: the magnetic energy, converted into heat by SPIONs, activates the cubic-to-hexagonal transition, and can thus be used as a remote stimulus to spike drug release “on-demand”. In addition, we show that the AMF-induced phase transition in magnetocubosomes steers the realignment of SPIONs into linear string assemblies and connect this effect with the change in their magnetic properties, observed at the bulk level. Finally, we assess the internalization ability and cytotoxicity of magnetocubosomes in vitro on HT29 adenocarcinoma cancer cells, in order to test the applicability of these smart carriers in drug delivery applications.     

Tuning the Magnetic Properties of Nanoparticles

The tremendous interest in magnetic nanoparticles (MNPs) is reflected in published research that ranges from novel methods of synthesis of unique nanoparticle shapes and composite structures to a large number of MNP characterization techniques, and finally to their use in many biomedical and nanotechnology-based applications. The knowledge gained from this vast body of research can be made more useful if we organize the associated results to correlate key magnetic properties with the parameters that influence them. Tuning these properties of MNPs will allow us to tailor nanoparticles for specific applications, thus increasing their effectiveness. The complex magnetic behavior exhibited by MNPs is governed by many factors; these factors can either improve or adversely affect the desired magnetic properties. In this report, we have outlined a matrix of parameters that can be varied to tune the magnetic properties of nanoparticles. For practical utility, this review focuses on the effect of size, shape, composition, and shell-core structure on saturation magnetization, coercivity, blocking temperature, and relaxation time.     

Preparation and Antibacterial Activities of Porous Silver‐doped β‐Tricalcium Phosphate Bioceramics

Infection is still a major concern in bone implants, especially in the implants with porous structures. As silver shows superior and broad‐spectrum antibacterial activity, porous silver‐doped β‐tricalcium phosphate (β‐TCP) bioceramics are prepared with 5% and 10% nanometer silver. The bioceramics show similar porous macrostructure with pure β‐TCP bioceramic, except slightly color change. They have almost identical microstructure to its pure β‐TCP counterpart under field emission scanning electron microscope. Their physical, chemical, and mechanical properties were investigated with X‐ray diffraction, Fourier transforming infrared spectrometer, and AG‐5kN, and no significant difference has been found between silver‐doped β‐TCP bioceramics and pure β‐TCP bioceramic. Bactericidal concentration of silver ions was detected in the solution soaked with the bioceramics. They can efficiently inhibit the growth of Staphylococcus epidermidis and Styphylococcus aureus, but show no cytotoxicity to L929 cells. It suggests that silver‐doped β‐TCP bioceramics can be developed into new type of bone substitutes with anti‐infection properties.     

Structural characterization of bioceramics and mineralized tissues based on Raman and XRD techniques

The design of new bioceramics requires a deep understanding of their structural characteristics using a combination of different characterization techniques. This paper offers an exhaustive Raman spectroscopy and X-ray diffraction study of two groups of bioceramics natural and synthetic, as well as of living tissues with different degrees of mineralization. Based on these results, two Raman-XRD correlation charts are proposed. Using a single Raman measurement, these charts are valuable tools for the identification of a number of structural parameters, such as the apatite phase percentage or crystallite size, of different calcium phosphate-based bioceramics and mineralized tissues.     

Microstructure and cytotoxicity of Al2O3-ZrO2 eutectic bioceramics with high mechanical properties prepared by laser floating zone melting

Developing new generation of strong, tough and stable bioceramics used in dental filed has been highly desired for attaining the clinical requirement of secure and reliable therapy. In this paper, a novel Al₂O₃-ZrO₂ eutectic bioceramics with nearly fully density and extremely aesthetic luster was in-situ prepared by innovative laser floating zone melting (LFZM) method. The influence of solidification rates on microstructure evolution, mechanical properties and cytotoxicity was investigated. The eutectic bioceramics displayed a special three dimensional interpenetrating microstructure evolving with increasing the solidification rate. The eutectic colony structure occurred when solidification rate overpassed 8?µm/s, and lamellar spacing was below 1?µm when solidification rate exceeded 30?µm/s. The eutectic bioceramics solidified at 100?µm/s exhibited optimal mechanical properties with an average hardness of 16.53?GPa, fracture toughness of 6.5?MPa?m^1/2 and flexural strength of 1.37?GPa. The cytotoxicity of Al₂O₃-ZrO₂ eutectic bioceramics was evaluated by MTT methods according to ISO 10993-5 standard. Non-cytotoxic behavior was detected for the eutectic bioceramics, indicating this eutectic bioceramic could be used as promising dental restoration material.     

Current advances concerning the most cited metal ions doped bioceramics and silicate-based bioactive glasses for bone tissue engineering

Studies related to biomaterials that stimulate the repair of living tissue have increased considerably, improving the quality of many people's lives that require surgery due to traumatic accidents, bone diseases, bone defects, and reconstructions. Among these biomaterials, bioceramics and bioactive glasses (BGs) have proved to be suitable for coating materials, cement, scaffolds, and nanoparticles, once they present good biocompatibility and degradability, able to generate osteoconduction on the surrounding tissue. However, the role of biomaterials in hard tissue engineering is not restricted to a structural replacement or for guiding tissue regeneration. Nowadays, it is expected that biomaterials develop a multifunctional role when implanted, orchestrating the process of tissue regeneration and providing to the body the capacity to heal itself. In this way, the incorporation of specific metal ions in bioceramics and BGs structure, including magnesium, silver, strontium, lithium, copper, iron, zinc, cobalt, and manganese are currently receiving enhanced interest as biomaterials for biomedical applications. When an ion is incorporated into the bioceramic structure, a new category of material is created, which has several unique properties that overcome the disadvantages of primitive material and favors its use in different biomedical applications. The doping can enhance handling properties, angiogenic and osteogenic performance, and antimicrobial activity. Therefore, this review aims to summarize the effect of selected metal ion dopants into bioceramics and silicate-based BGs in bone tissue engineering. Furthermore, new applications for doped bioceramics and BGs are highlighted, including cancer treatment and drug delivery.     

纳米结构铁氧体磁性材料的制备和应用

铁氧体纳米磁性材料是一类非常重要的无机功能材料,其应用涉及到电子、信息、航天航空、生物医学等领域。综述了纳米结构铁氧体磁性材料化学制备方法的研究进展,分析了相关纳米结构铁氧体磁性材料的制备工艺对磁性能的影响,以及它们的应用,展望了研究和开发纳米结构铁氧体磁性材料的新性能和新技术的应用前景。     

Mechanical properties of textured,multilayered alumina produced using electrophoretic deposition in a strong magnetic field

The mechanical properties of ceramics materials can be tailored by designing their microstructures. It had generally been difficult to utilize a magnetic field for controlling the texture of diamagnetic ceramics because of their extremely small susceptibility; however, the possibility of controlling the texture by a magnetic field occurred with the development of superconducting magnets. We demonstrate in this study that alumina/alumina laminar composites with alternate crystalline-oriented layers are produced by electrophoretic deposition in a strong magnetic field and that the bending strength of the laminar composite depended on the direction of the multilayered microstructure.     

A comprehensive study on the magnetic properties of nanocrystalline SrCo0.2Fe11.8O19 ceramics synthesized via diverse routes

The effects of the synthesis techniques: sol–gel combustion (SG), hydrothermal (HT) and co-precipitation (CP) on the structure, homogeneity, morphology and magnetic properties of SrCo_0.2Fe_11.8O₁₉ hexaferrite ceramics have methodically been explored by X-ray diffraction (XRD), laser particle analyzer, scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Structural analysis results revealed that the variety of the synthesis techniques evidently reflects variation in the lattice parameters and grain sizes. Moreover, diverse morphologies such as lamellar, disc-like and needle-shape for SG, HT and CT routes were observed, respectively. The maximum saturation magnetization (31.2 emu/g) and coercivity (4950 Oe) belonged to the co-precipitation technique owning to its higher phase purity, more homogeneity and larger crystalline size. Apparently, the softer ferrites were attainable by hydrothermal and sol–gel combustion routes, whereas, the co-precipitation technique led to harder magnets.     

The effect of the shape and size of the pores on the mechanical properties of porous HAP-based bioceramics

In this study, the influence of the shape and size of the pores on the mechanical properties of the obtained porous HAP-based bioceramics was investigated. The porous HAP-based bioceramics were obtained starting from spherical calcium hydroxyapatite powder, obtained by hydrothermal syntheses. The number of shapeless inter-agglomerate pores decreased and amount of spherical intra-agglomerate pores increased on increasing the sintering temperature from 1100 °C to 1250 °C. The shape of pores also changed with thermal treatment of specimens; the small pores remained spherical while the larger pores became more spherical in shape, as was proved by image analysis. A three-dimensional, finite element unit cell model was applied to evaluate the influence of pore shape on the mechanical strength of HAP ceramics. By analyzing the effect of the shape of pores to the fracture toughness of sintered porous HAP bioceramics, it was observed that the more spherical the pores were, the tougher became the bioceramics. After sintering at 1250 °C for 2 h, measured toughness was 1.31 MPa m^1/2, which is a relatively high value for this type of bioceramics.     

Multifunctional bioceramic-based composites reinforced with silica-coated carbon nanotube core-shell structures

Carbon nanotube (CNT) possesses eminent mechanical properties and has been widely utilized to toughen bioceramics. Major challenges associated with CNT-reinforced bioceramics include the inhomogeneous dispersion of CNTs and the insufficient interfacial strength between the two phases. To address such issues, this research describes the first use of silica-coated CNT (S-CNT) core-shell structures to reinforce bioceramics using hydroxyapatite (HA) as a representative matrix. HA-based composites with 0.1–2 wt% S-CNT are sintered by spark plasma sintering to investigate their mechanical and biological properties. It is found that when 1 wt% raw CNT (R-CNT) is added, very limited increases in fracture toughness (K_IC) is observed. By contrast, the incorporation of 1 wt% S-CNT increased the K_IC of HA by 101.7%. This is attributed to more homogeneously dispersed fillers and stronger interfacial strengths. MG63 cells cultured on the 1 wt% S-CNT/HA pellets are found to proliferate faster and possess significantly higher alkaline phosphatase activities than those grown on the HA compacts reinforced with 1 wt% R-CNT, probably by virtue of the released Si ions from the SiO2 shell. Therefore, the S-CNT core-shell structures can improve both mechanical and biological properties of HA more effectively than the conventionally used R-CNTs. The current study also presents a novel and effective approach to the enhancement of many other biomedical and structural materials through S-CNT incorporation.     

高梯度磁分离铬盐浸出浆液中的铬渣-Ⅰ.理论分析

提出了将铬渣从铬盐浸出浆液中去除的高梯度磁分离方法,建立了高梯度磁分离器的分离能力与设备参数、操作参数和物料性质参数之间关系的理论模型,定量讨论了磁场强度和操作温度对有效分离时间的影响.     

MXenes and MXene-based (nano)structures: A perspective on greener synthesis and biomedical prospects

Generally, MXenes have been widely prepared using hazardous/harmful etchants or fluoride-containing reagents through laborious protocols without environmentally-friendly features. Thus, greener and eco-friendly techniques with mild conditions and safer agents/materials for the synthesis and functionalization of these structures should be focused to reduce or avoid the utilization of toxic and hazardous chemical agents, enhancing the biocompatibility and biosafety criteria. The manufacturing of high-quality MXenes and their derivatives with up-scalability, simplicity, high yields, and cost-effectiveness advantages for clinical and biomedical purposes should be a priority for research in this field. MXenes with unique electronic/electric, mechanical, thermal, optical and magnetic properties can be applied to improve the efficacy and functionality of intelligent nanosystems targeted for biomedical purposes. However, in addition to the up-scalability and environmentally-benign criteria, other critical aspects regarding the stability and cost-effectiveness as well as optimized conditions and functionalization processes should be addressed. Herein, recent advances of greener synthesis approaches for designing MXenes as well as their biomedical potentials are deliberated, focusing on important challenges and future perspectives.     

Study on the high magnetic field processed ZnO based diluted magnetic semiconductors

Diluted magnetic semiconductors with the unique advantage of simultaneously manipulating the spin and charge of electrons possess potential applications in spintronics and quantum computing, which attracts long-term tremendous attention. It is pivotal and meaningful for practical application that room temperature ferromagnetism has been acquired successively in ZnO based diluted magnetic semiconductors. Although the unclear origin of ferromagnetism hampers their further development, there is a consensus that their magnetic properties are susceptible to materials preparation process. As an extreme condition with high-intensity energy, indirect contact and controllability, high magnetic field has been applied to various materials fabrication. Similarly, high magnetic field is employed in the preparation of ZnO based diluted magnetic semiconductors to adjust microstructural and magnetic properties, such as enhancing Curie temperature, inducing the transition from paramagnetism or diamagnetism to ferromagnetism, and improving ferromagnetism, while exploring the ferromagnetism mechanism from another perspective. In this brief perspective, recent study on the high magnetic field processed ZnO based diluted magnetic semiconductors is reviewed.